SU688133A3 - Method of producing moulded articles from polylauurinelactame - Google Patents

Description

I

This invention relates to the chemistry of high molecular weight compounds / specifically to methods for the anionic polymerization of lactams.

A known method for producing molded articles from polylaurinlactam is by anionic polymerization of lactam by melting the monomer — laurinlactam and uniformly introducing into it a catalyst and then an activator, followed by pouring into form 1.

The molded articles obtained by this method do not possess high physicochemical properties.

The purpose of the invention is to improve the physicochemical properties of products.

This is achieved by the fact that all stages of the polymerization process are carried out at a constant temperature in the range of 150-200 ° C.

According to the proposed method, laurinlactam is first melted and a catalyst is mixed into the prepared melt. After thorough mixing, the activator is added to the mixture. The catalyst is added to the laurinelactam melt, the subsequent activator rewrite and the polymerization is carried out at a constant

temperature It is most expedient to maintain the melt at a temperature of 150-20 ° C, and the best results are obtained at about 160 ° C.

In the implementation of the proposed method, the addition of a histivator can be made already after a short period of time (after the catalyst is mixed into the melt of laurinelactam). However, the activator can also be added much later, for example, approximately 48 hours after the addition of the catalyst, and no polymerization occurs at an intermediate time if the temperature of the mixture consisting of laurinelactam melt and catalyst is maintained at an appropriate CONSTANT temperature.

In order to entrain the melt of laurilactam with a catalyst or to mix the activator, a mixer is preferably used that provides rapid and homogeneous mixing.

In accordance with another embodiment of the process, all catalysts whose use is known in the production of polyamides can be used. The following catalysts are especially reliable: metallic sodium, sodium amide, alkaline salts of lactams, anhydrous ethyl alcohol and carbon dioxide, which is preferred. As an activator (initiator), compounds known in the preparation of polyamides can be used, for example isocyanates, such as phenyl isocyanate, substituted lactams, for example N-acyl lactams and N-cyanolactams, substituted urea and products of interaction of carbamic acid chloride with such heterocyclic compounds as imidazole . When phenylisocate is used, particularly good results are obtained, therefore the compound is an activator, which is preferably used in the implementation of the proposed method. The catalyst or catalysts and the activator or activators are added to the lactam melt in a total amount of about 0.01-5% by weight, preferably in an amount of about 0.1-0.6% by weight. When sodium amide, sodium metal or anhydrous ethyl alcohol is used as a catalyst, it is especially beneficial for the addition of the catalyst and the activator in an amount of about 0.38 IHF.% Based on the amount of lactam melt. When carbon dioxide is used as a catalyst, the melted lactam is predominantly saturated with carbon dioxide. In this case, it is sufficient to add the activator in an amount of about 0.2 wt.%. The present invention relates to the use of polylaurinlactal for the preparation of molded articles, especially when using casting techniques. After the catalyst is added to the monomeric laurinelactam melt, the subsequent addition of the activator and thorough mixing, the mixture begins to solidify about 1 minute after mixing. Hardening occurs evenly throughout the melt volume. The total thermal effect is only about b kcal / kg, and when solidifying, for example, casting from monomeric 5-caprolactam, the thermal effect is approximately 37 kcal. This small thermal effect (creates the advantage that the product cures under conditions of x at which no stresses arise due to uneven heat removal, which is often observed when using the known polyamides. Since the melt obtained according to the proposed invention melts with fluidity and heat supply is not a problem, molded products that have large sizes and any wall thickness can also be obtained. In addition, it turned out that the production of molded products due to the fact that the melt has a fluidity can be made almost without the use of pressure. in the molded articles obtained in accordance with the present invention, due to the small thermal effect during solidification, they remain well below the critical limits. Due to the fluidity of the melt, before the solidification in the molded bodies, shrink shells are formed. When using the obtained melt, it is possible to carry out a rather simple method of molding molded products having a complex geometric shape with sandy rods for cutting. The melt obtained with respect to recyclability is comparable with that of molten metals. When casting the resulting melt, the used casting mold does not need to be preheated or cooled. By using a mold that is preheated, e.g. before, a particularly smooth casting with a uniformly colored surface is obtained. The strength of the molded products after hardening increases early and then more slowly and reaches the maximum value in about 48 hours. The time after pouring, to which the casting can be removed from the mold, depends on the size, shape and weight of the molded molded body. Light parts can be removed from the mold immediately after solidification of the melt, i.e. after about 1 min after zapivka. Heavy products are kept in shape for a correspondingly longer time. The fluidity of the melt, its high wetting ability and high adhesion strength to the degreased surfaces of other materials allow, in addition, to produce combined materials and combined bodies. For example, non-porous composite bodies that contain finely cellular metallic fabric and fiberglass fabric can be obtained. In addition, reinforcement with metals can be provided in the molded bodies and the stiffness materials are increased

Different types, which are added to it when pouring a full-lurinlactam. Taking into account the excellent properties of polylaurinlactam (see Tables 1-4), it can be applied in numerous areas instead of metals.

Example. In a tank equipped with a stirrer and sealed to prevent air from entering, through which a continuous stream of nitrogen is passed in as a protective gas, 10 kg of laurinelactam is placed. The laurinectam is melted with stirring and then the temperature inside the vessel is adjusted to. Immediately thereafter, with stirring, 3.8 g of sodium amide was introduced into the container. The contents of the container are lured for 5 minutes. Then, 11.5 g of phenyl isocyanate was added to the mixture, after which the mixture thus obtained was vigorously stirred for 1 minute. Immediately after this, the melt is poured into the mold and allowed to harden. After solidification, the resulting molded body is removed from the mold. After 48 h, the molded body acquires the indicated properties.

Example 2. The process is carried out as in Example 1, but the melt of laurinelactam is saturated with carbon dioxide and only 5 g of phenyl isocyanate is used. In this case, carbon dioxide is not only a protective gas, but also a catalyst. The obtained molded product has the same properties as the product obtained in accordance with example 1.

Example C: To the melt stream of laurinelactam, whose temperature must be constantly ISOC, under conditions that exclude the presence of air, anhydrous ethyl alcohol is continuously fed at a constant rate as a catalyst. At the location below the catalyst feed site, phenyl isocyanate is continuously fed into the mixture as an activator in an amount corresponding to the amount of ethanol. After mixing, the stream, constantly maintained under conditions that exclude the presence of air, is poured into molds. The molded bodies obtained after solidification of the mixture have the same properties as the product obtained in accordance with Example 1.

68813.310

table 2

tagging.

dried over phosphorus pentoxide for

14 days;

14 days exposure at relative humidity

air 65% and temperature 20® С;

7 days of exposure to water at.

Depending on the recipe

VJCAT B 53 460

at -60 - -oso at -30 - 100

Up to several hours up to 4 months

Up to a year

Table 3

C217-271

€ 178

lo / fc 0.8-1.0 1.0-1.9

Khal / m 0.3 kgf / hGrad0.45

155

120-130

100-120

Claims (1)

1. US patent 3696075, class 260-78, publ. 1972 (prototype